diff --git a/TESTS/mbedmicro-rtos-mbed/rtostimer/main.cpp b/TESTS/mbedmicro-rtos-mbed/rtostimer/main.cpp
new file mode 100644
index 0000000000..581336bcdc
--- /dev/null
+++ b/TESTS/mbedmicro-rtos-mbed/rtostimer/main.cpp
@@ -0,0 +1,367 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2017 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "mbed.h"
+#include "greentea-client/test_env.h"
+#include "unity.h"
+#include "utest.h"
+#include "rtos.h"
+
+using namespace utest::v1;
+
+#define TEST_DELAY_MS 50
+#define TEST_DELAY2_MS 30
+#define TEST_DELAY_MS_DELTA 1
+#define TEST_RESTART_DELAY_MS 10
+
+#if TEST_RESTART_DELAY_MS >= TEST_DELAY_MS
+#error invalid TEST_RESTART_DELAY_MS value
+#endif
+
+void timer_callback(void const *arg)
+{
+    Semaphore *sem = (Semaphore *) arg;
+    sem->release();
+}
+
+/* In order to successfully run this test suite when compiled with --profile=debug
+ * error() has to be redefined as noop.
+ *
+ * RtosTimer calls RTX API which uses Event Recorder functionality. When compiled
+ * with MBED_TRAP_ERRORS_ENABLED=1 (set in debug profile) EvrRtxTimerError() calls error()
+ * which aborts test program.
+ */
+#if defined(MBED_TRAP_ERRORS_ENABLED) && MBED_TRAP_ERRORS_ENABLED
+void error(const char* format, ...) {
+    (void) format;
+}
+#endif
+
+/** Test one-shot not restarted when elapsed
+ *
+ * Given a one-shot timer
+ * When the timer is started
+ *     and given time elapses
+ * Then timer stops
+ *     and elapsed time matches given delay
+ *     and timer stays stopped
+ */
+void test_oneshot_not_restarted()
+{
+    Semaphore sem(1);
+    RtosTimer timer(mbed::callback(timer_callback, (void const *) &sem), osTimerOnce);
+    osStatus stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+
+    Timer t;
+    sem.wait(0);
+    stat = timer.start(TEST_DELAY_MS);
+    t.start();
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    int32_t slots = sem.wait(TEST_DELAY_MS + 1);
+    t.stop();
+    TEST_ASSERT_EQUAL(1, slots);
+    TEST_ASSERT_INT_WITHIN(TEST_DELAY_MS_DELTA * 1000, TEST_DELAY_MS * 1000, t.read_us());
+
+    slots = sem.wait(TEST_DELAY_MS + 1);
+    TEST_ASSERT_EQUAL(0, slots);
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+}
+
+/** Test periodic repeats continuously
+ *
+ * Given a periodic timer
+ * When timer is started
+ *     and given time elapses
+ * Then timer repeats its operation
+ * When timer is stopped
+ * Then timer stops operation
+ */
+void test_periodic_repeats()
+{
+    Semaphore sem(1);
+    RtosTimer timer(mbed::callback(timer_callback, (void const *) &sem), osTimerPeriodic);
+    osStatus stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+
+    Timer t;
+    sem.wait(0);
+    stat = timer.start(TEST_DELAY_MS);
+    t.start();
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    int32_t slots = sem.wait(TEST_DELAY_MS + 1);
+    int t1 = t.read_us();
+    TEST_ASSERT_EQUAL(1, slots);
+    TEST_ASSERT_INT_WITHIN(TEST_DELAY_MS_DELTA * 1000, TEST_DELAY_MS * 1000, t1);
+
+    slots = sem.wait(TEST_DELAY_MS + 1);
+    t.stop();
+    TEST_ASSERT_EQUAL(1, slots);
+    TEST_ASSERT_INT_WITHIN(TEST_DELAY_MS_DELTA * 1000, TEST_DELAY_MS * 1000, t.read_us() - t1);
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    slots = sem.wait(TEST_DELAY_MS + 1);
+    TEST_ASSERT_EQUAL(0, slots);
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+}
+
+/** Test timer can be restarted
+ *
+ * Given a one-shot timer
+ * When the timer is started
+ *     and @a start is called again before given time elapses
+ *     and given time elapses
+ * Then timer stops
+ *     and elapsed time is greater than original delay
+ */
+void test_restart()
+{
+    Semaphore sem(1);
+    RtosTimer timer(mbed::callback(timer_callback, (void const *) &sem), osTimerOnce);
+    osStatus stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+
+    Timer t;
+    sem.wait(0);
+    stat = timer.start(TEST_DELAY_MS);
+    t.start();
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    int32_t slots = sem.wait(TEST_RESTART_DELAY_MS);
+    TEST_ASSERT_EQUAL(0, slots);
+
+    stat = timer.start(TEST_DELAY_MS);
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    slots = sem.wait(TEST_DELAY_MS + 1);
+    t.stop();
+    TEST_ASSERT_EQUAL(1, slots);
+    TEST_ASSERT_INT_WITHIN(TEST_DELAY_MS_DELTA * 1000, (TEST_DELAY_MS + TEST_RESTART_DELAY_MS) * 1000, t.read_us());
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+}
+
+/** Test timer can be started again
+ *
+ * Given a one-shot timer
+ * When the timer is started
+ *     and given time elapses
+ * Then timer stops
+ * When the timer is started again
+ *     and given time elapses
+ * Then timer stops again
+ */
+void test_start_again()
+{
+    Semaphore sem(1);
+    RtosTimer timer(mbed::callback(timer_callback, (void const *) &sem), osTimerOnce);
+    osStatus stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+
+    sem.wait(0);
+    stat = timer.start(TEST_DELAY_MS);
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    int32_t slots = sem.wait(TEST_DELAY_MS + 1);
+    TEST_ASSERT_EQUAL(1, slots);
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+
+    stat = timer.start(TEST_DELAY_MS);
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    slots = sem.wait(TEST_DELAY_MS + 1);
+    TEST_ASSERT_EQUAL(1, slots);
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+}
+
+/** Test timer restart updates delay
+ *
+ * Given a one-shot timer
+ * When the timer is started
+ *     and @a start is called again with a different delay before given time elapses
+ *     and updated delay elapses
+ * Then timer stops
+ *     and time elapsed since the second @a start call matches updated delay
+ */
+void test_restart_updates_delay()
+{
+    Semaphore sem(1);
+    RtosTimer timer(mbed::callback(timer_callback, (void const *) &sem), osTimerOnce);
+    osStatus stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+
+    sem.wait(0);
+    stat = timer.start(TEST_DELAY_MS);
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    int32_t slots = sem.wait(TEST_RESTART_DELAY_MS);
+    TEST_ASSERT_EQUAL(0, slots);
+
+    Timer t;
+    stat = timer.start(TEST_DELAY2_MS);
+    t.start();
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    slots = sem.wait(TEST_DELAY2_MS + 1);
+    t.stop();
+    TEST_ASSERT_EQUAL(1, slots);
+    TEST_ASSERT_INT_WITHIN(TEST_DELAY_MS_DELTA * 1000, TEST_DELAY2_MS * 1000, t.read_us());
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+}
+
+/** Test timer is created in stopped state
+ *
+ * Given a one-shot timer
+ * When the timer has not been started
+ * Then the timer is stopped
+ */
+void test_created_stopped()
+{
+    RtosTimer timer(mbed::callback(timer_callback, (void const *) NULL), osTimerOnce);
+    osStatus stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+}
+
+/** Test one-shot can be stopped
+ *
+ * Given a one-shot timer
+ * When the timer is started
+ *     and timer is stopped while still running
+ * Then timer stops operation
+ */
+void test_stop()
+{
+    Semaphore sem(1);
+    RtosTimer timer(mbed::callback(timer_callback, (void const *) &sem), osTimerOnce);
+    osStatus stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+
+    sem.wait(0);
+    stat = timer.start(TEST_DELAY_MS);
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    int32_t slots = sem.wait(TEST_RESTART_DELAY_MS);
+    TEST_ASSERT_EQUAL(0, slots);
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    slots = sem.wait(TEST_DELAY_MS + 1);
+    TEST_ASSERT_EQUAL(0, slots);
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+}
+
+/** Test timer started with infinite delay
+ *
+ * Given a one-shot timer
+ * When the timer is started with @a osWaitForever delay
+ * Then @a start return status is @a osOK
+ */
+void test_wait_forever()
+{
+    RtosTimer timer(mbed::callback(timer_callback, (void const *) NULL), osTimerOnce);
+
+    osStatus stat = timer.start(osWaitForever);
+    TEST_ASSERT_EQUAL(osOK, stat);
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osOK, stat);
+}
+
+/** Test timer started with zero delay
+ *
+ * Given a one-shot timer
+ * When the timer is started with 0 delay
+ * Then @a start return status is @a osErrorParameter
+ */
+void test_no_wait()
+{
+    RtosTimer timer(mbed::callback(timer_callback, (void const *) NULL), osTimerOnce);
+
+    osStatus stat = timer.start(0);
+    TEST_ASSERT_EQUAL(osErrorParameter, stat);
+
+    stat = timer.stop();
+    TEST_ASSERT_EQUAL(osErrorResource, stat);
+}
+
+void timer_isr_call(void const *arg)
+{
+    RtosTimer *timer = (RtosTimer *) arg;
+    osStatus stat = timer->start(TEST_DELAY_MS);
+    TEST_ASSERT_EQUAL(osErrorISR, stat);
+
+    stat = timer->stop();
+    TEST_ASSERT_EQUAL(osErrorISR, stat);
+}
+
+/** Test timer method calls from an ISR fail
+ *
+ * Given a one-shot timer
+ * When a timer method is called from an ISR
+ * Then method return status is @a osErrorISR
+ */
+void test_isr_calls_fail()
+{
+    RtosTimer timer(mbed::callback(timer_callback, (void const *) NULL), osTimerOnce);
+
+    Ticker ticker;
+    ticker.attach(mbed::callback(timer_isr_call, (void const *) &timer), (float) TEST_DELAY_MS / 1000.0);
+
+    wait_ms(TEST_DELAY_MS + 1);
+}
+
+utest::v1::status_t test_setup(const size_t number_of_cases)
+{
+    GREENTEA_SETUP(5, "default_auto");
+    return verbose_test_setup_handler(number_of_cases);
+}
+
+Case cases[] = {
+    Case("Test one-shot not restarted when elapsed", test_oneshot_not_restarted),
+    Case("Test periodic repeats continuously", test_periodic_repeats),
+    Case("Test timer can be restarted while running", test_restart),
+    Case("Test stopped timer can be started again", test_start_again),
+    Case("Test restart changes timeout", test_restart_updates_delay),
+    Case("Test can be stopped", test_stop),
+    Case("Test timer is created in stopped state", test_created_stopped),
+    Case("Test timer started with infinite delay", test_wait_forever),
+    Case("Test timer started with zero delay", test_no_wait),
+    Case("Test calls from ISR fail", test_isr_calls_fail)
+};
+
+Specification specification(test_setup, cases);
+
+int main()
+{
+    return !Harness::run(specification);
+}
diff --git a/rtos/RtosTimer.h b/rtos/RtosTimer.h
index 3abef47c94..d96de829e1 100644
--- a/rtos/RtosTimer.h
+++ b/rtos/RtosTimer.h
@@ -131,13 +131,21 @@ public:
     }
 
     /** Stop the timer.
-      @return  status code that indicates the execution status of the function.
+      @return  status code that indicates the execution status of the function:
+          @a osOK the timer has been stopped.
+          @a osErrorISR @a stop cannot be called from interrupt service routines.
+          @a osErrorParameter internal error.
+          @a osErrorResource the timer is not running.
     */
     osStatus stop(void);
 
-    /** Start the timer.
-      @param   millisec  time delay value of the timer.
-      @return  status code that indicates the execution status of the function.
+    /** Start or restart the timer.
+      @param   millisec  non-zero value of the timer.
+      @return  status code that indicates the execution status of the function:
+          @a osOK the timer has been started or restarted.
+          @a osErrorISR @a start cannot be called from interrupt service routines.
+          @a osErrorParameter internal error or incorrect parameter value.
+          @a osErrorResource internal error (the timer is in an invalid timer state).
     */
     osStatus start(uint32_t millisec);